I made serious mistake during design of pumping station thinking LM75A has non-volatile memory for configuration parameters. Actually this IC haven’t such ability as store configuration between power-ups.
Fortunately I have connection to TWI pins on both sensor board and wiring, so decided to create some “hardware config file” basing on ATTiny13. I have created Arduino sketch to test approach and it is working just fine, but tiny13 has no hardware TWI implementation comparing to ATMega168. After some research over the net I found nice implementation of AVR-300 (Software TWI) by Peter Fleury: http://homepage.hispeed.ch/peterfleury/avr-software.html#libs
Here are 2 PCBs, one is test board for LM75 sensor, second is ATTiny13 for software implementation of TWI:
My configuration board is still not working despite simplicity of the library. I haven’t found why, but my guess is that internal RC oscillator is not suitable for this. Will try to run with external crystal today.
Update: I had made it working!